Sir, a ranula is a mucus extravasation 'pseudocyst' that frequently occurs within the body of the sublingual salivary gland or ducts, and less frequently from minor salivary glands in the floor of the mouth.1 We are seeing increasing numbers of ranulae which appear to be related to traumatic causes attributable to radiograph holders for bitewings or periapicals, and in the younger patient, removable orthodontic appliances. A recent clinical example of a 13-year-old female highlights this. She developed a large painful swelling in the floor of her mouth (Figs 1 and 2) after wearing a functional appliance.

Figure 1
figure 1

The sizeable floor of mouth swelling

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The risks of fixed and removable orthodontic appliances to the hard and soft tissues of the oral cavity are well documented. However, a risk that is frequently omitted in the literature is the potential for trauma and obstruction to the major and minor salivary glands of the floor of the mouth. It is possible for a functional orthodontic appliance to damage or impinge on the sublingual salivary gland and mucosa, resulting in the spillage of mucin into the surrounding soft tissues. The result can cause serious morbidity to the patient. On this occasion the patient required surgical management requiring general anesthesia.

We suggest that due care and consideration be given to using any instrumentation or appliances that could be traumatic to the delicate structures of the soft tissues of the mucosa, especially the floor of the mouth.

Figure 2
figure 2

The offending appliance

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